Electrical measuring instrument.



W. M. BRADSI'IPJRI,a ELECTRICAL MEASURING INSTRUMENL APPLICATION FILEDAPR. 15. 1914.

11. %53 Patented Jam. 15, 1918..

- mvmmn ATTORNEY n stars PATENT onion.

WILLIAM ivr. BRADSHAW, or WILKINSBURG. PENNSYLVANIA, ASSIGNOR ToWESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATIDN 0FPENNSYL- VANIA.

ELECTRICAL MEASURING INSTRUMENT.

Specification of Letters Patent.

Patented Jan, 115, 1213,

AppI-Lgstion filed April 15, 1914. Serial No. 831,985.

T 0 all whom it may concern:

Be it known that l, VVILLIAM M. BRAD- sI-IAW, a citizen of the UnitedStates, and a resident of Wilkinsburg, in the county of Allegheny andState of Pennsylvania, have invented a new and useful Improvement inElectrical Measuring Instruments, of whlch the following is aspecification.

My invention relates to electrical measuring instruments, andparticularly to motor meters for use in connection with alternatingcurrent circuits.

An object of my invention is to provide an electrical measuringinstrument of the induction type having a permanent magnet that servesthe double purpose of acting as a return path for the electromagneticlines of force, and as a damping magnet.

Another object of my invention is to provide a meter which is compact inconstruc tion and possesses such novel features as adapt it to theservice to be performed.

Figure 1 of the accompanying drawings is a top plan View of anelectrical measuring instrument embodying my invention, and Fig. 2 is afront view, partially in elevation and partially in section, of theinstrument shown in Fig. 1.

A magnetizable core member 1 has a plurality of polar projections 2, 3,4 and 5, which are spaced apart and around which are disposed thecurrent windings 6 and 7', for purposes hereinafter described. Avoltage'winding 8 is disposed upon the central leg 9 of the magnetizablecore 1. The free ends of the projections 2, 3, 4t and 5 and the oppositeportion of the body portion of the magnetizable core 1 have asubstantially cylindrical curvature. A light weight metal cylinder 10 isopen at its lower end and is provided with a plurality of arms 11 at itsupper end which terminate at its central ads for supporting the same.The cylindrical member 10 constitutes the armature of the motor and isdisposed around the magnetizable core 1, substantially as shown in thedrawing. A permanent magnet 12 of substantially annular form is disposedaround the rotatable armature 10 for the double purpose of actin as areturn path for the magnetic lines of force from the magnetizable core 1and as a damping magnet for the armature. The poles 13 and 1 1 of themagnet 12 are located adjacent to the cylindrically curved end of themagnetizable member 1. A soft iron member 15 is attached by a screw 16to the magnet 12 adjacent to the polar projection 2, 3, 4 and 5. Amember 17 is attached to the opposite sides of the magnet 12 by screws18 and extends within the armature 10 to support the magnetizable member1, which is attached thereto by screws 19, and to support the armatureat a point 20 which coincides with its central axis. A member 21 is alsoattached to the magnet 12 by the screws 18 to serve as a guide for theshaft 22 of the armature 10. The shaft 22 is associated, at its upperend, with an integrating mechanism, the dials 23 of which cooperate withpointers 2 1 for the purpose of registering the rotations of thearmature.

The windings 6 and 7 are usually connected in series relation to theconductors that carry the energy to be measured and the Winding 8 isusually connected in shunt relation to such conductors. Since there is arelatively large number of turns in the Windin 8, the current flowingthrough the same Wlll not be in phase with the current flowing throughthe windings 6 and 7 which have a relatively small number of turns. Thetwo magnetic fluxes that difler in phase will pass from the polarprojections 2, 3, 4 and 5 through the armature to the member 15 and, byreason of their phase relation, will cause the armature to rotate. Themagnetic lines of force, after intercepting the armature, pass throughthe magnetic circuit provided by the permanent magnet 12 to the oppositeend of the magnetizable core 1. Since the member 12 is a permanentmagnet, a local magnetic circuit will also be established from the poles13 and 14 through the armature 10, the cylindrically curved end of themagnetizable member 1 and an air gap 25 between the said poles to dampor retard the rotation of the armature. The shifting field set up in theair gap between the member 15 and the polar projections 2, 3, 4 and 5 isidentical with the field set up in other instruments of the inductiontype, and hence needs no further explanation.

While the device hereinbefore described is adapted for the measurementof energy, it is primarily a motor, and I accordingly intend that theappended claims shall be construed to cover motors irrespective of thepurposes for which they are utilized.

Although the specific form of construction shown is preferred, it isobvious that many modifications may be made within the spirit of theinvention, and I desire to include all such modifications Within thescope of the appended claims.

I claim as my invention:

1. An electrical measuring instrument comprising a magnetizable corehaving p0- lar projections that are Spaced apart, a cylindrical armaturerotatably mounted to surround the magnetizable core, and a substantiallyannular permanent magnet disposed around the cylindrical armature andhaving its poles disposed adjacent the portion of the core opposite tothe polar projections.

2. An electrical measuring instrument comprising a magnet-izable corehaving pola 1' projections that are spaced apart, a potentlal windingupon the core, a current winding disposed upon the polar projections, acylindrical armature rotatably mounted to surround the core, and asubstantially annular permanent magnet disposed around the cylindricalarmature and having its poles disposed adjacent the portion ofthe coreopposite to the polar projections.

3. An electrical measuring instrument comprising a magnetizable corehaving polar projections that are spaced apart, a potential winding uponthe core, a current winding disposed upon the polar projections, acylindrical armature rotatably mounted to surround the core, and a meansfor conducting the magnetic lines of force from one end of themagnetizable core through an external circuit to the other end of thesame and for damping the movement of the armature.

4:. In an electrical measuring instrument, the combination with amagnetizable core having polar projections, of a cylindrical armaturerotatably disposed around the said core, and a magnetizable memberdisposed around the said armature for damping the rotation of the sameand for returning'the magnetic lines of force to the said magnctizablecore.

5. In an electrical measuring instrument, the combination with amagnetizable core, of a cylindrical armature rotatably disposed aroundthe said core, a permanent magnet disposed around the said armature, andmeans attached to the said permanent magnet for supporting the saidmagnetizable core and the said armature.

.6. In a motor-meter, the combination with a "magnetizable core memberhaving spacedapart polar projections and constituting the driving memberof the meter, of a cylindrical armature rotatively disposed around theentire core member, and a substantially annular permanent magnetdisposed around the ari'nature and having'its poles adjacent the end ofthe core member opposite to the spaced-apart polar projections.

In an electrical measuring instrument, the combination with amagnetizable core having polar projections, a potential Winding on thecore and a current winding disposed, on the polar projections, of acylindrical armature surrounding the magnetizable core, a permanentmagnet disposed around the said armature, and means attached to thepermanent magnet to support the magnetizable core and the said armature.

8. In an electrical measuring instrument, the combination with amagnetizable core, of a cylindrical armature rotatably supported at itsupper end, a permanent magnet, and means attached to the said permanentmagnet for supporting the said armature and magnetizable core.

9. In an electrical measuring instrument, the combination with amagnetizable core having spaced-apart polar projections, a potentialwinding on the core and current windings disposed on the polarprojections, of an armature entirely surrounding the magnetizable core,and a single keeper and damping ma et surrounding the armature.

10. In an e ectrical measuring instrument, the combination with amagnetizable core having spaced-apart polar projections, a potentialwinding on the core and current windings disposed on the projections, ofan armature entirely surrounding the core, and a single means fordamping the movements of the armature and for returnin the magnetic fluxfrom the polar projections to the core.

'11. An electrical measuring instrument comprising a magnetizable corehaving spaced-apart polar projections and constituting the actuatingelectromagnet of the instrument, a cylindrical armature surrounding theentire core and a permanent magnet surrounding the armature for dampingthe movement thereof and for constituting a keeper for the core.

12. An electrical measuring instrument comprising a magnetizable corehaving spaced-apart polar projections and constituting the actuatingelectromagnet of the instrument, a cylindrical armature surrounding theentire core and a permanent magnet surrounding the armature for dampingthe movement thereof and for constituting a return magnetic path for thelines of force from one end of the magnetizable core to the other.

13. In a motor-meter, the combination with a magnetizable core memberconstituting the driving member of the meter, of a cylindrical armaturerotatably disposed around the entire core, and means disposed around thearmature for damping the movement of the same and for constituting a re-In testimony whereof, I have hereunto subscribed my name this 25th dayof Man,

B. B. HINES.

